Setting this variable to 0 (off, false, no) disables the logging of file updates to the log file. This means that the data file recovery process (using the library routine C$RECOVER) is impossible. However, because rollback information is maintained internally by the runtime, the program can still use the transaction management system to START, COMMIT, and ROLLBACK transactions. This variable can be set programmatically with the SET ENVIRONMENT verb. The default setting is 1 (on, true, yes).